I can do 4+ feet away. I can hang the lights from the ceiling. When you say it will burn my plants, do you say that because of the power of the MH light or the heat? The heat is not a problem beacause of the hood I'm using for the lights. Plus, I'll have a fan blowing on the lights.

So, instead of a indoor greenhouse, I'll make a bench. Here is what I think I'll do.

Sounds cool. MH lights put off a lot of heat, but the brightness of the lights can sunburn some plants if to close.

Do you think that if the MH is 30" away from the plants, it might still be too close?

What is the wattage of the MH? 30" is probably too close for a 400W bulb. Maybe not for a 250 bulb

Usually I hear (I don't own a MH light myself) 4-5 feet is recommended. However, as mentioned above, the strength/power of your MH light makes a difference. Also, some orchids like more light then others.

MY LIGHTS ARE 175 WATTS. ALSO, THE LIGHT FIXTURE HAS A GLASS UNDER THE LIGHTBULB, WHICH REDIRECTS THE HEAT TO VENTS ON THE TOP OF THE LIGHT FIXTURE.

The glass will help and the lower wattage will help too. MH lights can sunburn your orchids just like you can sunburn if your out in the sun to much. Search sun burned orchids and you'll see how the leaves burn, turn yellow, and can die. A fan blowing air around your orchids will help keep the leaves cool and help to prevent burning.

Well if you have 2 of them, as indicated by your drawing, 30" may still be too close for some phals. I think it's something you just need to test out. Start higher up, and slowly lower it. My guess is you'll need at least 3' clearance, if not more. 350W of light, heat or not, is gonna be very bright under 3'

I've been thinking about you said and I think I'll use 1 light instead of 2. What do you think?